1. Field of the Invention
The present invention relates to an electric distribution system which provides a unique electrical take-off wherein rotatable electrical contacts may be moved between a storage position and an active position wherein they are urged by spring clips into spring biased contact with the electrical bus bars.
2. Description of the Prior Art
It has been known to provide overhead busways containing bus bars for distributing electricity through various take-off devices to equipment, appliances, lighting and other articles requiring a source of electrical energy in order to operate. It has been known to provide busways having a top wall and side walls with electrical bus bars secured to the interior surfaces thereof for delivering electrical current to a take-off device. Means are provided for attaching and supporting such bus bars to structural supports and a suitable source of electrical energy. See, generally, U.S. Pat. No. 5,449,056 which is owned by the assignee of the present application.
It has been known to provide rotary take-off devices which have radially projecting rigid blades which are adapted to engage bus bars located in the busway track. One of the problems with such designs has been the extremely limited range of movement and, as a result, the lack of ability to accommodate variations in the size of the track in which the take-off device is installed. In addition, such devices are generally limited in current capacity to lamp loads typically in the range of about 3 to 5 amperes.
A product sold under the trade designation "Chan-L-Wire" provides a take-off device wherein sharp barbs puncture a soft electrically insulating cover on the bus bars in order to establish electrical contact. The barbs are not spring-loaded and rely on interference fit between the take-off device and the wires in the track. The take-off capacity of the system is said to be about 20 amperes.
It has also been suggested to employ a flat spring-tempered conductive material to facilitate electrical contact. See, generally, Global Track Pro by Nordic Aluminum. In this system a rotating cam urges a blade out of a housing. The blade engages a bus bar. The blade is inherently flexible and is said to exert a pressure on the bus bar. The system is believed to offer only about 5 amperes of current. Any effort to enlarge the blade would tend to reduce the ability of the blade to flex and also require more space.
It has also been known to employ a coil spring-loaded system wherein the electrical contact pin is urged toward the bus bar by a wound coil spring. A shortcoming of such a system is that the coil spring requires significant space to operate in both the extended and compressed state. See Starline Busway System B60 Busway Series. See, also, U.S. Pat. No. 3,877,553 and U.S. Pat. No. 5,503,259.
In spite of the prior art, there remains a substantial need for an electrical take-off system which will provide adequate take-off current, is of a reasonable size, adapts to variations in track sizes, and is reliable and easy to use.